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Discussion Starter · #1 ·
Am I the only one who finds it odd Lotus wants you to change brake fluid every year? That is way more frequent than any other vehicle I have owned. Thoughts on why?
 

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High performance fluid will absorb water and under stress (heat) cause performance issues. It's well worth the investment and time. You could probably get away with 24 months but I wouldn't go longer than that. If you still have your original fluid and you haven't changed it yet- just take a look at it. It's gross. You'll want to change it lol
 

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also the clutch is off the brake fluid ... and adds lots of containment

also id guess Lotus assume enthusiastic driving, as compared to putting about in a honda...
 

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I bought mine last year and changed the fluid. It was pretty dark caramel.

1 track day later and a few thousand street miles and I will check again before may. If its not dark again, I may just wing it and change it at the end of the season instead.
 

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IMO it's due to the clutch sharing the same reservoir. If you keep it seperate the fluid lasts much longer. Google clutch dust and you'll read about it.
 

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Discussion Starter · #6 ·
Thanks guy for the input. Nessal, are you saying clutch dust is getting past the hydraulic piston seal and actually getting into the brake fluid? Interesting..
 

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Bleed your breaks and you'll see it- tiny metal flakes in your old fluid. The particles work their way past the actuator
 

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IMO it's due to the clutch sharing the same reservoir. If you keep it seperate the fluid lasts much longer. Google clutch dust and you'll read about it.
The slave cylinder on the Elise/Exige is outside the clutch housing. It's not getting clutch dust inside the fluid. The "clutch dust" people are talking about Chevy's that use concentric slave cylinders inside the clutch housing.

The reason the fluid gets dark is a reaction to moisture from the atmosphere being absorbed into the fluid, temperature effects, corrosion effects, and the degradation of the rubber seals.

Changing the fluid often and using a fluid that is rated correctly for the system will help prevent these issues. Using a high temp fluid like Motul RBF will keep the fluid from boiling, but water absorption will still be an issue. Using Castrol SRF would be the ultimate, since it has the highest boiling temp, and absorbs less moisture.
 

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Bleed your breaks and you'll see it- tiny metal flakes in your old fluid. The particles work their way past the actuator
That would be from the master cylinder piston, cylinder bore walls, or brake caliper pistons if anywhere..

If "metal particles" could get past your master cylinder piston rod seals and caliper piston seals... then the liquid could get out.
 

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The slave cylinder on the Elise/Exige is outside the clutch housing. It's not getting clutch dust inside the fluid. The "clutch dust" people are talking about Chevy's that use concentric slave cylinders inside the clutch housing.

The reason the fluid gets dark is a reaction to moisture from the atmosphere being absorbed into the fluid, temperature effects, corrosion effects, and the degradation of the rubber seals.

Changing the fluid often and using a fluid that is rated correctly for the system will help prevent these issues. Using a high temp fluid like Motul RBF will keep the fluid from boiling, but water absorption will still be an issue. Using Castrol SRF would be the ultimate, since it has the highest boiling temp, and absorbs less moisture.
On your first point about Chevy's I agree. I have a Corvette and the general consensus it to swap out the fluid, especially if you drag race the car.

My mechanic actually prefers the Motul RBF to the Castrol SRF. I like the Castrol SRF (except for the price) but my mechanic didn't want to use it in the Lotus. He preps a lot of the Lotus Cup cars so I did as he wished.

San
 
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